CN113960787B - Binary grating array for realizing symmetrical lattice feature patterns and method thereof - Google Patents

Abstract

The present invention discloses a binary grating array and a method for realizing a symmetrical lattice characteristic pattern. The period of a grating corresponding to a pair of symmetrical points of the symmetrical lattice characteristic pattern is obtained according to the wavelength of incident light and the divergence angle of the pair of symmetrical points of the symmetrical lattice characteristic pattern. Then, according to the spatial position direction of the pair of light points, the etching direction of the corresponding grating unit is designed. Finally, according to the beam splitting condition of the grating corresponding to the pair of symmetrical points, the etching depth of the grating is obtained. Each grating structure is designed in this way, and the grating structures are combined to form a microstructure unit of a final diffraction grating element. The binary grating array has a simple structure, a simple preparation method, and has the advantages of strong operability, good reliability, high energy utilization, strong reproducibility, weak diffraction light, etc. It has a wide range of applications and is suitable for the realization of all symmetrical lattice characteristic patterns.

Description

A binary grating array and method for realizing symmetrical dot matrix characteristic pattern

Technical Field

The invention relates to the technical field of laser beam transformation, and in particular to a binary grating array for realizing a symmetrical lattice characteristic pattern and a method thereof.

Background Art

At present, in the outdoor laser display industries such as laser medical treatment, laser scanning, and advertising, it is usually necessary to convert a single laser light source into a dot matrix of light beams, and these dot matrices are usually symmetrical patterns. With the development of these industries, higher and higher requirements are placed on the structural simplicity and reproducibility of beam conversion elements. Nowadays, there are mainly the following methods for generating characteristic patterns of symmetrical dot matrices:

The first one is based on the principle of diffraction optics and obtains the phase information required by the diffraction element according to the desired lattice pattern to obtain the etching information of the diffraction optical element.

The second method is based on the principle of two-dimensional Dammann grating. The beam splitting in one-dimensional direction is first calculated to obtain the structure of the one-dimensional Dammann grating, and then the structure is orthogonally processed to obtain a two-dimensional symmetrical dot pattern.

However, the above two solutions have their own shortcomings. The first one has the disadvantages of stray light, serious background light, and low energy utilization rate. In order to improve its light energy utilization rate, it can only increase the etching order of the diffractive optical element, which will greatly increase the processing difficulty and uncertainty, and is not conducive to the replication and mass production of components; the second solution has a small scope of application and can only realize orthogonal equally spaced dot patterns, and cannot realize other forms of dot patterns.

Therefore, the existing technology still needs to be improved and developed.

Summary of the invention

The object of the present invention is to provide a binary grating array and method for realizing a symmetrical dot matrix feature pattern, aiming to solve one or more problems existing in the prior art.

The technical solution of the present invention is as follows:

The present technical solution provides a method for preparing a binary grating array that realizes a symmetrical lattice feature pattern, which specifically includes the following steps:

S1: Get the wavelength of incident light;

S2: obtaining the period of the grating corresponding to a pair of symmetrical points according to the wavelength of the incident light and the divergence angle of a pair of symmetrical points of the symmetrical lattice characteristic pattern;

S3: obtaining the etching direction of the grating corresponding to the pair of symmetrical points according to the directions of the spatial positions of the pair of symmetrical points;

S4: according to the beam splitting conditions of the grating corresponding to the pair of symmetrical points, obtaining the etching depth of the grating;

S5: Repeat S2 to S5 to traverse all symmetrical points in the symmetrical dot matrix feature pattern until all corresponding gratings are obtained, and finally the entire binary grating array is obtained.

Furthermore, the S5 specifically includes the following steps:

s51: judging whether all symmetrical points in the symmetrical lattice feature pattern have been traversed, if yes, jumping to s52, if not, jumping to S2;

s52: Get the entire binary grating array.

Furthermore, in S2, the period of the corresponding grating is obtained according to the grating equation d=λ/sinθ, wherein θ is the divergence angle of the symmetric point, λ is the wavelength of the incident light, and d is the period of the corresponding grating.

Further, in S4, the beam splitting condition of the grating corresponding to the pair of symmetrical points is one-to-two beam splitting or one-to-three beam splitting.

Furthermore, when the grating realizes a one-to-two beam splitting function, in S4, the etching depth of the grating is obtained according to the structure of the Dammann grating.

Furthermore, when the grating realizes a one-to-three beam splitting function, in S4, the etching depth of the grating is obtained according to the structure of the Dammann grating and the material used for the grating.

Furthermore, the transverse structure of the grating is determined according to the structure of the Dammann grating, and the longitudinal depth of the grating is determined by the material used for the grating.

Furthermore, the longitudinal depth of the grating is determined according to the formula: etching depth = λ/[2*(n-1)], wherein λ is the wavelength of the incident light and n is the refractive index of the material used to make the grating.

Furthermore, the grating is made of fused quartz glass or ordinary glass or ZnSe.

The technical solution also provides a set of binary grating arrays that realize symmetrical lattice characteristic patterns, which are prepared by any of the preparation methods described above.

From the above, it can be known that the technical solution obtains the period of the grating corresponding to the pair of symmetrical points according to the wavelength λ of the incident light and the divergence angle of one pair of symmetrical points of the symmetrical lattice feature pattern, and then designs the etching direction of the corresponding grating unit according to the direction of the spatial position of the pair of light spots. Finally, because for each pair of light spots, the corresponding grating generally realizes a one-to-two beam splitting function, at this time, the etching depth of the grating is obtained according to the structure of the Dammann grating and the material used by the grating; if the central bright spot is required at the same time, the corresponding grating realizes a one-to-three beam splitting function, and at this time, the etching depth of the grating must be obtained according to the structure of the Dammann grating and the material used by the grating; each grating structure is designed in this way, and combined to form the microstructure unit of the final diffraction grating element; the binary grating array has a simple structure, simple preparation method steps, and has the advantages of strong operability, good reliability, high energy utilization, strong reproducibility, weak diffraction light, etc. It has a wide range of applications and is suitable for the realization of all symmetrical lattice feature patterns.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow chart showing the steps of a method for preparing a binary grating array for realizing a symmetrical lattice feature pattern in the present invention.

FIG. 2 is a rendering of an eight-point mirror with a central bright spot in the present invention.

FIG. 3 is a schematic diagram of the grating microstructure corresponding to FIG. 1 in the present invention.

FIG. 4 is a diagram showing the effect of grating beam splitting one into three in the present invention.

DETAILED DESCRIPTION

The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and/or reference letters in different examples, and this repetition is for the purpose of simplicity and clarity, which itself does not indicate the relationship between the various embodiments and/or settings discussed. In addition, the present invention provides various specific examples of processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and/or the use of other materials.

As shown in FIG1 , a method for preparing a binary grating array for realizing a symmetrical lattice feature pattern specifically comprises the following steps:

S1: Get the wavelength λ of the incident light;

S2: obtaining the period of the grating corresponding to a pair of symmetrical points according to the wavelength λ of the incident light and the divergence angle of a pair of symmetrical points of the symmetrical lattice characteristic pattern;

S3: obtaining the etching direction of the grating corresponding to the pair of symmetrical points according to the directions of the spatial positions of the pair of symmetrical points;

S4: according to the beam splitting conditions of the grating corresponding to the pair of symmetrical points, obtaining the etching depth of the grating;

S5: Repeat S2 to S5 to traverse all symmetrical points in the symmetrical dot matrix feature pattern until all corresponding gratings are obtained, and finally the entire binary grating array is obtained.

In some specific embodiments, the S5 specifically includes the following steps:

s51: judging whether all symmetrical points in the symmetrical lattice feature pattern have been traversed, if yes, jumping to s52, if not, jumping to S2;

s52: Get the entire binary grating array.

In some specific embodiments, in S2, the corresponding grating period is obtained according to the grating equation d=λ/sinθ, where θ is the divergence angle of the symmetric point, λ is the wavelength of the incident light (here refers to the laser), and d is the corresponding grating period.

In some specific embodiments, in S4, the beam splitting conditions of the grating corresponding to the pair of symmetrical points are set according to actual needs. For example, for each pair of symmetrical light spots, the corresponding grating realizes a one-to-two beam splitting function; and if a central bright spot is required in addition to a pair of symmetrical light spots, the corresponding grating realizes a one-to-three beam splitting function.

When the grating realizes the one-to-two beam splitting function, in S4, the etching depth of the grating can be obtained according to the structure of the Damman grating (the Damman grating was first proposed by Damman and Goertler in 1971. It can efficiently generate a uniform light intensity dot matrix position phase grating in the far field of Fourier transform for incident monochromatic light. It can produce arbitrarily arranged dot matrix and the grating uniformity is not affected by the incident light wave).

When the grating realizes a one-to-three beam splitting function, in S4, the etching depth of the grating can be obtained according to the structure of the Dammann grating and the material used for the grating.

The etching depth of the grating is controlled according to the formula: etching depth = λ/[2*(n-1)], λ is the wavelength of the incident light, and n is the refractive index of the material used to make the grating; the transverse structure of the grating (i.e., the xy plane) is determined according to the structure of the Dammann grating, and the longitudinal depth of the grating (i.e., the depth in the z direction) is determined by the etching depth formula.

In some specific embodiments, the grating is made of different materials according to actual needs, including but not limited to fused quartz glass or ordinary glass or ZnSe (zinc selenide).

The technical solution also protects a binary grating array that realizes a symmetrical lattice feature pattern, which is prepared by the preparation method as described above.

According to the above-mentioned binary grating array for realizing symmetrical dot matrix characteristic patterns and its preparation method, the following embodiments are listed for illustration:

For a laser with a wavelength of 532nm, an eight-point mirror pattern as shown in Figure 2 is designed, and the divergence angle (half angle) corresponding to each group of light spots (i.e., a pair of symmetrical points) is 10°; the component material used for the grating is fused quartz.

According to the above conditions, it can be concluded that the period of the grating corresponding to one group of symmetrical points is 3.06um. Obviously, to realize this eight-point mirror symmetrical dot matrix pattern, it can be realized by four grating units with the same grating period but 45° difference in etching direction, as shown in Figure 3; in addition, for each grating, the function it realizes is to split the light beam into three, and its effect is shown in Figure 4. The etching depth of the grating can be obtained according to the structure of the Dammann grating and the material used for the grating, thereby determining the structure of each grating, and then obtaining the entire binary grating array.

In the description of this specification, the description with reference to the terms "one embodiment", "certain embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims (10)

1. The preparation method of the binary grating array for realizing the symmetrical lattice feature patterns is characterized by comprising the following steps of:

s1: acquiring the wavelength of incident light;

S2: obtaining the period of the grating corresponding to the symmetrical points according to the wavelength of the incident light and the divergence angle of one pair of symmetrical points of the symmetrical lattice feature graph;

S3: obtaining the etching direction of the grating corresponding to the symmetrical points according to the direction of the spatial position of the symmetrical points;

s4: obtaining the etching depth of the grating according to the beam splitting condition of the grating corresponding to the symmetrical points;

s5: and repeatedly executing S2-S4, traversing all symmetrical points in the symmetrical lattice feature graph until all corresponding gratings are obtained, and finally obtaining the whole binary grating array.

2. The method for preparing the binary grating array for realizing the symmetrical lattice feature pattern according to claim 1, wherein the step S5 specifically comprises the following steps:

s51: judging whether all symmetrical points in the symmetrical dot matrix feature graph are traversed once, if yes, jumping to S52, and if not, jumping to S2;

s52: obtaining the whole binary grating array.

3. The method for producing a binary grating array for realizing a symmetrical dot matrix feature pattern according to claim 1, wherein in S2, the method is performed according to the grating equationAnd obtaining the period of the corresponding grating, wherein θ is the divergence angle of the symmetrical point, λ is the wavelength of incident light, and d is the period of the corresponding grating.

4. The method for manufacturing a binary grating array for implementing a symmetrical dot matrix feature pattern according to claim 1, wherein in S4, the beam splitting condition of the grating corresponding to the symmetrical dot is one-to-two beam splitting or one-to-three beam splitting.

5. The method for preparing a binary grating array for implementing a symmetrical lattice feature pattern according to claim 4, wherein when the grating implements a one-to-two beam splitting function, in the step S4, the etching depth of the grating is obtained according to the structure of the dammann grating.

6. The method for preparing a binary grating array for realizing symmetric lattice feature patterns according to claim 4, wherein when the grating realizes a beam splitting function of one-to-three, in the step S4, the etching depth of the grating is obtained according to the structure of the dammann grating and the material adopted by the grating.

7. The method of claim 6, wherein the transverse structure of the grating is determined based on the structure of the dammann grating.

8. The method for manufacturing a binary grating array for realizing a symmetrical dot matrix feature pattern according to claim 7, characterized in that it is according to the formula: etch depth = λ/[2 x (n-1) ] determines the longitudinal depth of the grating, where λ is the wavelength of the incident light and n is the refractive index of the material from which the grating is made.

9. The method for producing a binary grating array for realizing a symmetrical dot matrix feature pattern according to claim 8, wherein the grating is made of fused silica glass or common glass or ZnSe.

10. A set of binary grating arrays for realizing symmetrical dot matrix feature patterns, characterized in that they are produced by the production method according to any one of claims 1 to 9.